Experimental characterization of an uniaxial angle cut whispering gallery mode resonator

The usual configuration of uniaxial whispering gallery mode resonators is a disk shaped geometry where the optic axis points along the symmetry axis, a so called z-cut resonator. Recently x-cut resonators, where the optic axis lies in the equatorial plane, became of interest as they enable extremely broadband second harmonic generation. In this paper we report on the properties of a more generalized system, the so called angle-cut resonator, where the optic axis exhibits an arbitrary angle against the symmetry axis. We show experimentally that the modal structure and quality factors are similar to common resonators but that the polarization properties differ quite significantly: due to the asymmetry the polarization depends on the equatorial position and is, in general, elliptical

DFT study of graphene antidot lattices: The roles of geometry relaxation and spin

Graphene sheets with regular perforations, dubbed as antidot lattices, have theoretically been predicted to have a number of interesting properties. Their recent experimental realization with lattice constants below 100 nanometers stresses the urgency of a thorough understanding of their electronic properties. In this work we perform calculations of the band structure for various hydrogen-passivated hole geometries using both spin-polarized density functional theory (DFT) and DFT based tight-binding (DFTB) and address the importance of relaxation of the structures using either method or a combination thereof. We find from DFT that all structures investigated have band gaps ranging from 0.2 eV to 1.5 eV. Band gap sizes and general trends are well captured by DFTB with band gaps agreeing within about 0.2 eV even for very small structures. A combination of the two methods is found to offer a good trade-off between computational cost and accuracy. Both methods predict non-degenerate midgap states for certain antidot hole symmetries. The inclusion of spin results in a spin-splitting of these states as well as magnetic moments obeying the Lieb theorem. The local spin texture of both magnetic and non-magnetic symmetries is addressed

Improvement of lung preservation - From experiment to clinical practice

Background. Reperfusion injury represents a severe early complication following lung transplantation. Among the pathogenetic factors, the high potassium content of Euro-Collins(R) solution is discussed. Material and Methods: In a pig model of orthotopic left-sided lung transplantation we investigated the effect of Euro-Collins solution (EC: n=6) versus low potassium dextran (LPD: Perfadex(R): n = 6). Sham-operated (n = 6) animals served as control. Transplant function, cellular energy metabolism and endothelial morphology served as parameters. In a clinical investigation, 124 patients were evaluated following single (EC: n = 31; LPD n = 37) or double (EC: n = 17; LPD n = 39) lung transplantation, whose organs where preserved with EC (n = 48) or LPD (n = 76). Duration of ischemia, duration of ventilation and stay on ICU were registered. Primary transplant function was evaluated according to AaDO(2) values. Cause of early death (30 days) was declared. Results: Experimental results: After flush with EC and 18 h ischemia, a reduction of tissue ATP content (p < 0.01 vs inital value and LPD) was noted. Endothelial damage after ischemia was severe (p < 0.05 vs control), paO(2) was significantly decreased. Clinical results: In the LPD group, duration of ischemia was longer for the grafts transplanted first (SLTx and DLTx: p = 0.0009) as well as second (2. organ DLTx: p = 0.045). Primary transplant function was improved (day 0: SLTx: p = 0.0015; DLTx: p = 0.0095, both vs EC). Duration of ventilation and stay on ICU were shorter (n.s.). Reperfusion injury-associated death was reduced from 8% (EC) to 0 (LPD). Conclusion: In experimental lung preservation, LPD lead to an improved graft function. These results were confirmed in clinical lung transplantation. Clinical lung preservation, therefore, should be carried out by use of LPD. Copyright (C) 2002 S. Karger AG, Basel

Searching for the pulsar in G18.95-1.1: Discovery of an X-ray point source and associated synchrotron nebula with Chandra

Using the Chandra X-ray Observatory, we have pinpointed the location of a faint X-ray point source (CXOUJ182913.1-125113) and an associated diffuse nebula in the composite supernova remnant G18.95-1.1. These objects appear to be the long-sought pulsar and its wind nebula. The X-ray spectrum of the point source is best described by an absorbed powerlaw model with Gamma=1.6 and an N_H of ~1x10^(22) cm^(-2). This model predicts a relatively low unabsorbed X-ray luminosity of about L_X (0.5-8.0keV) = 4.1x10^(31)D_2^2 erg s^(-1), where D_2 is the distance in units of 2kpc. The best-fitted model of the diffuse nebula is a combination of thermal (kT = 0.48keV) and non-thermal (1.4 < Gamma < 1.9) emission. The unabsorbed X-ray luminosity of L_X = 5.4x10^(33)D_2^2 erg s^(-1) in the 0.5-8keV energy band seems to be largely dominated by the thermal component from the SNR, providing 87% of L_X in this band. No radio or X-ray pulsations have been reported for CXOUJ182913.1-125113. If we assume an age of ~5300yr for G18.95-1.1 and use the X-ray luminosity for the pulsar and the wind nebula together with the relationship between spin-down luminosity (via magnetic dipole radiation) and period, we estimate the pulsar's period to be P = 0.4s. Compared to other rotation-powered pulsars, a magnetic field of 2.2x10^(13)G is implied by its location in the P-Pdot diagram, a value which is close to that of the quantum critical field.Comment: 8 pages, 3 Figures, accepted for publication in Ap

Assessing numbers and faces: a prerequisite for improving access to lymphatic filariasis morbidity care

Concerted efforts to eliminate lymphatic filariasis worldwide have registered success; multiple rounds of mass drug administration have led to the interruption of transmission in many previously endemic areas. However, the management of patients with established clinical disease (e.g., lymphoedema, hydrocoele and acute dermatolymphangioadenitis) has not been addressed sufficiently. Two recent studies from Malawi underscore the need for accurate epidemiological and clinical data, and comprehensive morbidity assessments across various domains of daily life. Addressing these issues will guide the implementation of programmes to improve access to treatment and disability prevention for affected individuals in Malawi and beyon

Phase resolved spectroscopy and Kepler photometry of the ultracompact AM CVn binary SDSS J190817.07+394036.4

{\it Kepler} satellite photometry and phase-resolved spectroscopy of the ultracompact AM CVn type binary SDSS J190817.07+394036.4 are presented. The average spectra reveal a variety of weak metal lines of different species, including silicon, sulphur and magnesium as well as many lines of nitrogen, beside the strong absorption lines of neutral helium. The phase-folded spectra and the Doppler tomograms reveal an S-wave in emission in the core of the He I 4471 \AA\,absorption line at a period of $P_{\rm orb}=1085.7\pm2.8$\,sec identifying this as the orbital period of the system. The Si II, Mg II and the core of some He I lines show an S-wave in absorption with a phase offset of $170\pm15^\circ$ compared to the S-wave in emission. The N II, Si III and some helium lines do not show any phase variability at all. The spectroscopic orbital period is in excellent agreement with a period at $P_{\rm orb}=1085.108(9)$\,sec detected in the three year {\it Kepler} lightcurve. A Fourier analysis of the Q6 to Q17 short cadence data obtained by {\it Kepler} revealed a large number of frequencies above the noise level where the majority shows a large variability in frequency and amplitude. In an O-C analysis we measured a $\vert\dot{P}\vert\sim1.0\,$x$\,10^{-8}\,$s\,s$^{-1}$ for some of the strongest variations and set a limit for the orbital period to be $\vert\dot{P}\vert<10^{-10}$s\,s$^{-1}$. The shape of the phase folded lightcurve on the orbital period indicates the motion of the bright spot. Models of the system were constructed to see whether the phases of the radial velocity curves and the lightcurve variation can be combined to a coherent picture. However, from the measured phases neither the absorption nor the emission can be explained to originate in the bright spot.Comment: Accepted for publication in MNRAS, 15 pages, 14 figures, 5 table

Naturally-phasematched second harmonic generation in a whispering gallery mode resonator

We demonstrate for the first time natural phase matching for optical frequency doubling in a high-Q whispering gallery mode resonator made of Lithium Niobate. A conversion efficiency of 9% is achieved at 30 micro Watt in-coupled continuous wave pump power. The observed saturation pump power of 3.2 mW is almost two orders of magnitude lower than the state-of-the-art. This suggests an application of our frequency doubler as a source of non-classical light requiring only a low-power pump, which easily can be quantum noise limited. Our theoretical analysis of the three-wave mixing in a whispering gallery mode resonator provides the relative conversion efficiencies for frequency doubling in various modes

Controlling the transport of an ion: Classical and quantum mechanical solutions

We investigate the performance of different control techniques for ion transport in state-of-the-art segmented miniaturized ion traps. We employ numerical optimization of classical trajectories and quantum wavepacket propagation as well as analytical solutions derived from invariant based inverse engineering and geometric optimal control. We find that accurate shuttling can be performed with operation times below the trap oscillation period. The maximum speed is limited by the maximum acceleration that can be exerted on the ion. When using controls obtained from classical dynamics for wavepacket propagation, wavepacket squeezing is the only quantum effect that comes into play for a large range of trapping parameters. We show that this can be corrected by a compensating force derived from invariant based inverse engineering, without a significant increase in the operation time

Atrial Natriuretic Peptide Protects against Histamine-Induced Endothelial Barrier Dysfunction in Vivo

Endothelial barrier dysfunction is a hallmark of many severe pathologies, including sepsis or atherosclerosis. The cardiovascular hormone atrial natriuretic peptide (ANP) has increasingly been suggested to counteract endothelial leakage. Surprisingly, the precise in vivo relevance of these observations has never been evaluated. Thus, we aimed to clarify this issue and, moreover, to identify the permeability-controlling subcellular systems that are targeted by ANP. Histamine was used as important pro-inflammatory, permeability-increasing stimulus. Measurements of fluorescein isothiocyanate (FITC)-dextran extravasation from venules of the mouse cremaster muscle and rat hematocrit values were performed to judge changes of endothelial permeability in vivo. It is noteworthy that ANP strongly reduced the histamine-evoked endothelial barrier dysfunction in vivo. In vitro, ANP blocked the breakdown of transendothelial electrical resistance (TEER) induced by histamine. Moreover, as judged by immunocytochemistry and Western blot analysis, ANP inhibited changes of vascular endothelial (VE)-cadherin, β-catenin, and p120ctn morphology; VE-cadherin and myosin light chain 2 (MLC2) phosphorylation; and F-actin stress fiber formation. These changes seem to be predominantly mediated by the natriuretic peptide receptor (NPR)-A, but not by NPR-C. In summary, we revealed ANP as a potent endothelial barrier protecting agent in vivo and identified adherens junctions and the contractile apparatus as subcellular systems targeted by ANP. Thus, our study highlights ANP as an interesting pharmacological compound opening new therapeutic options for preventing endothelial leakage

Unresolved grief and its consequences. A nationwide follow-up of teenage loss of a parent to cancer 6-9 years earlier.

PURPOSE: The early loss of a parent is a tragedy and a serious life event. This study investigated grief resolution and morbidity in cancer-bereaved teenagers 6 to 9 years after the loss of a parent to cancer. METHODS: In a nationwide population-based study of 622 of 851 (73 %) youths who as teenagers 6 to 9 years earlier had lost a parent to cancer, we explored the magnitude of unresolved grief and its association with psychological and physiological morbidity. Participants answered a study-specific anonymous questionnaire including questions about if they had worked through their grief and about their current health. RESULTS: Six to nine years post-loss 49 % reported unresolved grief (8 % no and 41 % a little grief resolution). They had, in comparison with youths reporting resolved grief, statistically significantly elevated risks, e.g. for insomnia (sons' relative risk (RR) 2.3, 95 % CI 1.3-4.0; daughters' RR 1.7, 95 % CI 1.1-2.7), fatigue (sons' RR 1.8, 95 % CI 1.3-2.5; daughters' RR 1.4, 95 % CI 1.1-1.7) and moderate to severe depression, i.e. score >9, PHQ-9 (sons' RR 3.6, 95 % CI 1.4-8.8; daughters' RR 1.8, 95 % CI 1.1-3.1). Associations remained for insomnia in sons, exhaustion in daughters and fatigue in both sons and daughters when depression, negative intrusive thoughts and avoiding reminders of the parents' disease or death were included in a model. CONCLUSIONS: Approximately half of cancer-bereaved youth report no or little grief resolution 6 to 9 years post-loss, which is associated with fatigue, sleeping problems and depressive symptoms